Radio system



June 29 1 926. 1,590,635

I 15.6. MccAA RADIVOI SYSTEM 7 Filed May 5. 1925 2 Sheets-Shag; 1

, l 'gii 8.2 ave $2 cages/$41 BY My. 5w

ms ATTORNEY June 29 1926.

D. G. M cAA RADIO SYSTEM Filed'May 5. 1925 2 Sheets-Sheet 2 INVENTOR HIS ATTORNEY Patented June 29, 1926, j

UNITED. STATES DAVID G. MOCAA, OF LANCASTER; PENNSYLVAYIA, ASSIGNOR TO THE ELECTRIC AP- PATENT-caries.

PARATUS CO., OF PARKESBURG, PENNSYLVANIA, A. CORPORATION. 0! PENNSYL- vanm.

name s'vsrnu.

. Application filed Hayli, 1925. Serial 1T0. 28,067.

My invention relates to the reception of radio or high frequency energy, in radio "systems or in systems in which high -frequency energy is transmitted over a conductor or conductors extending between transmitting and receiving stations, without substantial interference or disturbance due to other radio or high frequency energy pro-' duced. either artificially or by natural ele.c tricity, as by static,-atmospherics, etc,

It is characteristic of my invention that there is effected clear or sharp differentiation, in the receptionof high or radio frequency energy, representing controls 7 or telephonic or telegraphic signals, between signalor control-representing energy of low amplitude, notwithstanding the simultaneous existence. of disturbing high frequency oscillations of high amplitude, and

such as are caused by static, atmospherics or other forms of natural-or artificial electricity.

In accordance with my present invention, a circuit or path is detuned with respect to the frequency of the desired oscillations, and preferably in such sense that the undesired oscillations will have a frequency lower than the frequency of the desired oscillations, and there is operatively related to the de- 'tuned circuit or path a plurality of couplings, either magnetic or capacitative, or in.

, part magnetic and in part capacitative', said couplings opposing and neutralizing each other as regards the undesired oscillations and all other oscillations differing in the same sense from the desired oscillations, as

regards their effect upon a signal-translat ing circuit or device, while as regards oscillations of the desired frequency said couplings do not neutralize each other and there are accordingly effective in the signal-translating circuit or device oscillations of the desired frequency, which are accordingly translated into signals or controls without substantial disturbance by the undesired oscillations. v

In accordance with myinvention, a balance is efiected for both the desired and undesired oscillations by opposing and new tralizing couplings, and the balance is destroyed by a path tuned to one of said kinds of oscillations, as regards the desired oscillations, whereby they only will afiect the signal-translating circuit or instrinnent.

Further in accordance with my invention,

impedance, however, does not e'flect the neutralizationor balance of oscillations of undesired frequency, since it is not opaque thereto."

My invention resides in the method and v apparatus of the character hereinafter described and claimed. I 7 I For an understanding of my method, and for an illustration of some of the various forms my apparatus may take, reference may be had to the accompanying drawings, in which:

- Fig. 1 is a diagrammatic view of radio receiving apparatus embodying my invention,

Fig. l is a diagrammatic view of a modification utilizable in case the static oscillations have a higher frequency than the de- '80 sired or signal oscillations.

' Fig, '2 is a diagrammatic View of aimodification of Fig. 1, in which the detuned circuit or path is not in immediate or direct energy-transfer relation with the natural or other transmitting medium.

Figs. 3, 4, 5 and 6 are diagrammatic views of further modifications embodying my 1nvention.

Figs. 7, 8 and 8 are diagrammatic views of modifications utilizing couplings in part magnetic and in part capacitative.

, Fig. 9 is a diagrammatic view of a modification in which the balancing andneutral- 'izing couplings are all capacitative,

' in the drawings, A represents generically any absorption structure of a radio receiving system, either an open antenna path, or, if desired, a closed circuit or loop, and

broadly, any circuit or path'receiving energy from the natural media or more or less remotely coupled to such a circuit or path, and

representing also a conductor system entending between transmitting and receiving quency or carrier wave conductor systems;

For brevity, however, my invention will be controls, but more particularly for signaling, including telegraphic and telephonic til til

ice

stations as utilised, for example, in high frelltt signaling, it understood that the translating instrument T, hereinafter referred to,

represents genericall any. translating instrument, as a telep one, loud speaker or a control instrument ofgany character.

Referring to Fig. 1, in the path between the antenna A and earth' or counter-capacity E are included the variable tu'ningcondenserC, which may be omitted, if suitable or desirable, and the rimary P. Coupled to the primary P, pre erably closely, are the secondaries S and S whose circuits may be regarded'as in parallelwith each other or having'in common the' tuning condenser C and the. variable inductance or variometer c, which may or may not be used, as'circumstances may require. Serial'lyin the circuit of the secondary S are included the inductance L and condenser C in parallel with each other and either or both variable for tuning the circuit L, C to resonance with the frequency of the desired or signal telephone or the like, or the primary of aos cillations. In circuit with the secondary S ris a variable inductance L In shuntto thecondenser C may be connected any signal-translating circuit or a detector, as a crystal detector or equivalent. In the example illustrated, however, there is connected across the condenser C the grid .or input circuit of a thermionic vacuum tube V, which epresents generically either a detector tube or the-first of one or more stages of radio frequency In the anode or plate' circuit of the tube V is a winding T, which represents generi-- cally a signal-translating instrument, as a 1 transformer whose secondary is connected quency ampl' er.

,either to the gridcircuit of a succeeding .vacuum tube 0 rating either as a radio.

frequency am hfier, detector, or audio frenatural period of the antenna path may be either longer or shorter than the period of the energy it is desired 'to receive, and in either case static or the like excites the antenna system or path by supplying energy thereto,'which then takes the form of oscillations whose predominant frequency is determined by the capacity and inductance of the antenna path or other circuit or path which absorbs the static energy. the

*example illustrated by Fig. 1, however, the natural. period of the antenna path is longer couplings of S and S to the amplifier tubes.

than the periodof the signal oscillations'to be received. a v .I

With the switch 8 open andthe switch a closed, thereby short circuiting the inductance L the circuit 8 ,10, C is tuned to resonance with the desired oscillations,

which are present in the antenna path as forced oscillations, by varying the inductance of 'v or' the capacity of the condenser C or both. Under these circumstances,

both desired and undesired oscillations will affect the grid circuit of the tube V, and currents representing both the desired and undesired effects will be present in the instrument or winding T. i

Switches 8 and a may noW be closed, which in effect places thesecondary S in parallel with the secondary S both coils being now related in common to the inductance 'v and condenser 0 and setting up equal and opposite electromotive-forces across 'v, G thereb 1n effect causing zero difference of potential between the points :v

and 3 by virtue of the equal and opposite rimaryP, with no effect by either desired or undo,- sired oscillations upon the input circuit of the tube V.

s is opened, whereupon thereis introduced Switch 8 is now left closed and switch into the circuit of the secondary Shigh or substantially infinite impedance, with respect to oscillations-of the desired or signal frequency, because the parallel-resonant circuit L, C is tuned to the frequency of the signal oscillations.

Whereas the parallel resonant circuit L,

Ci 'oflers high or infinite impedance to the .desired' frequency, it offers far lower impedance to the oscillations caused by orrepresenting static or other disturbances,

and as to them the reactance of the combination of L and C is inductive, and because of this fact there is introduced into the clrcuit of the secondary S for balancing purposes,

a small inductance L this being effected by opening the switch 8 With the switch 8 open, the inductance L may be adjusted to effect or restore the neutralizing balance as regards oscillations of a frequency of undesired oscillations, to wit, those of all frequencies lower than the-fre ue'ncy of the desired signal oscillations.

en the inductance L is brought into circuit, there may be necessitated small readjustment of the-inductance '0 and/or condenser C, for it is essential with the switch 8 open that the circuits L C '0 be in resonance with the desired oscillations, and simultaneously the parallel resonance path L, C is in resona'nce with the desired oscillations. With the switches in the position last described, the circuit is in its operative condition, with the result that all undesired oscillations, namely, those of a frequency lowerthan the frequency ofthe desired oshigh impedance 'n one of' the circuits as caused by the inductance L and its capacity 0*, and there are accordingly impressed.

uponthe input circuit of the tube V oscillations of the desired frequency, with the result that in the ultimate signal-translating p j ustablecondenser instrument T the desired signals are manitested or heard, to the substantial or entire exclusion otefiects due to undersired oscillations.

While the circuit LQC introduces high or infinite impedance to oscillations of the desired frequency, oscillations of frequency higher than that of the desired oscillations may also be present, but these are eiie'ctually suppressed by the usual tuning operation as effected by the inductance *2) and/or condenser (3 h Referring to Fig. 1, there is utilized in lieu of the inductance lb of Fig. 1 an ad- C This is to provide for the case where the antenna path is detuned to a natural frequency higher than the frequency ofthe desired signal oscillations. in such case, the parallel resonant circuit L, C is in eifect a capacitative reactance for all frequencies higher than the frequency of the desiredoscillations, and in consequence, there is required to effect a balance'a capacitative reactance' in the circuit of the secondary S and such is provided by the adjustable condenser 0 Referring to Fig. 2, the primary P is no lon er in the antenna or other absorptionpat, but is in a circuit coupled thereto through the transformer P S the circuit P, S being detuned with respect to the frequency of the desired or si nal oscilla trons, and this may be effected y the variable condenser C"=. The circuits coupled to the primary P are similar to those described in connection with Fig. 1, and their operation is that above described, for in this case again there is-detuning with respect to the signal oscillations, not directly in the absorbmg circuit or path, but in a circuit more or less remote therefrom. T

In the example of Fig. 2, the antenna path. may be tuned to the frequency of the desired signal oscillations by adjusting the condenser C or the priinar P or either of them, though it will be un erstood also that the antenna path may be detuned to the same frequency to which the circuit P," S

7 C is detuned. Preferably, however, the

antenna path is tuned to the signal frequency, while the intervening circuit or path 13- detuned, for under these circumstances static or disturbing effects small or moderate in magnitude will effect-oscillations in the antenna pathof the same frequency asthe desired oscillations, but will have small eflfect upon the. detuned circuit P, S", C, whereas static or disturbing efiects of great ma nitude will, notwithstanding the tuning o -the antenna tothe signal freguency, shock-excite the detuned circuit P C, setting up therein oscillations oi frequency different from that of the desired oscillations.

It will be understood, of course, that in case the detuning is'to a frequenc higher than the frequency of the desire oscillations, the inductance L will a ain he supplanted by a ca acity such as as and for the reasons in icated in connection with,

Fig. 1. v

' Referring to Fig. 3, the arrangement is fundamentally that described in connection with Figs. let seq. in that the circuit of the secondary S is, with the switch a open and the switch s closed toward the right, tuned to the desired oscillations by the variable condenser G with or without'the assistance of the variable inductance '41. By throwing the switch 8 toward the lel 'tv and maintaining switch 3 open, the secondary S is brought into series with the secondary S thereby detuning the circuit S *0, C and the secondaries are coupled in such sense to the primary P that their electro-motive forces as applied to the terminals er the condenser C are in opposition to each cther. Under these'circumstances, a balance 15 cf fected, and neither desired nor undesired oscillations have any effect upon the input circuit of the tube V. However, leaving the switch 8 in its left hand position and closing the switch 8?, and by adjusting the cuit of the tube V, with resultant manifestation of the desired signal in or by the instrument T; Bringing the inductance L and condenser C -into shunt with the secondary S and thereb effecting a path at aero reactance for the requency of the desired 12 oscillations, has the further effect of retuning the circuit of the secondary S to the desired frequency. The branch L, G when so adjusted toresonance for the Sig nal frequency, offers capacitative reactance R25 I to all longer waves, including those of static due to detuning of the antenna path to a longer-period. To compensate for this capacltative reactance, there is utilized in the I circuit of the secondary S for the same rea- 16a variable condenser C or the variable induc ,tance L, or both of them,- to resonance for son that. the capacity (I is utilized in Fig. 1, a variable condenser C brought into circuit by closure of the switch 8 that ofthe desired oscillations, two

ccupledto the secondary whose circuit,

tuned by the condenser(} to the desired signal frequency, is the input circuit'of the tu e V. In shunt to either of the primaries P or P are connected the variable condenser C and variable inductance L, in series with each other, brought into circuit by opening the switch 8 in which case the antenna path is still detuned with respect to the signaloscillations. The inductance L and capacity C effect across the terminals 0 the primary "P a branch tuned tothe frequency of the desired oscillations.

Here again the branch L, G when brought into circuit, upsets the previous balance, during which neither signal nor static oscillations affected tube V, and oscillations of signal frequency are now withheld from the primary P, and the. secondary S is influenced by oscillations of signal frequency in the rimary P In ig. 5 the primaries P and P are again equally and oppositely closely coupled to the secondary S, but they are disposed in parallel branches inthe antenna path, which as before is detuned to longer wave length than that ofthe desired oscillations. In

series withone 0f the primaries, as P is theparallel resonance circuit L, C, and in the branch containing-the primary P is introduced the compensating inductance L as described in connection with Fig. 1.

Referring to Fig. 6, there is shown an arrangement in general similar to that of my. prior application Serial No. 722,246, filed- June 25, 1924, modified by application thereto of the principles ofmy present'invention,

and particularly an arrangement of the character of Fig. llhereof.

As in my aforesaid prior application, the

signal-translatingcircuit is coupled through. the secondary S- equally andoppositely with the primaries P and P in the antenna I ath, which in this case is again detuned wit respect to the signal frequency, and particularly to a frequency lower than the frequency of the signal oscillations. Brought into parallel with the primary P, as upon opening the switch a, is an inductance L, which, with switch 8 open, still leaves the antenna path detuned to the desired frequency. Coupled to the inductance L is the inductance or coilL, in' the anode circuit of a ra- .dio frequency amplifier tube V whose input circuit is related to theantenna path substantially in the same manner as the input circuit of the-tube V' in Fig. 1,. For this purpose, the primary P, in the antennapath, 1s again associated with the secondaries S and S with which are associated the tuning inductance o, and tuning capacity C, with the parallel resonance path L, C in circuit with S v and a compensating inductance L in circuit with the secondary S. By this system, comparable to that of Fig. 1, onlyoscillations of desired frequency can influence the input circuit of the amplifier tube V, and in consequence, the am lified oscillations of desired frequency in t e coil L in'the anode circuit reduces the inductive reactance of the coil L whereby the primary 1? is.-

robbed of oscillations of signal frequency, permitting the primary P at signal frequency to influence the input circuitof the -L'-, and therefore influenced by static or other undesired, oscillations, together with the condenser K, thereby impressing upon the grid of the tube V, as regards undesired or static frequencies, electro-motive-forces equal and opposite to those impressed thereon through the intra-tu capacity K Referring to Fig. 7, there is an embodiment of my invention in which the couplings are in part magnetic and in part capacltative. The magnetic coupling between the detuned antenna and the signal-translating instrument is provided by the primary P and secondary S, the condenser C as before tuning the secondary circuit to the frequency of the desired oscillations. From a point w of elevated or suitable potential in the antenna,

absorption or other detuned path, there is effected a capacitative coupling to the point 2 by and through the coupling capacities O and C", or either ofthem alone, whereby, with the switch s closed, the magnetic coupling P, S,-if in proper sense, which may be determined by the direction of winding or sense of connection of either P or S, is opposed and neutralized by the capacitative coupling as regards oscillations of both desired and undesired frequencies, whereby thein ut circuit of the tube V is not affected by eit er the desiredsignal or. the disturbances, By opening the switche however, there is brought into series in the capacitative coupling path a high or substantially infinite impedance when the parallel reso nance' path L, C is tuned to the'frequency of the desired oscillations, with the result that the balance upon the input circuit "of .the tube V as regards oscillations of desired fregenerall similar system in that there are.

involve both magnetic and capacitative couplings for balancing out both desired and un esired oscillations as regards the input circuit of the tube V. 'In this case, however, the parallel resonance circuit L, C is applied to the magnetic coupling, and, as shown, in a ath'or branch in parallel to the secondary S In this case, when the switch '8 is closed and the closed circuit L, C attuned to the desired frequency, there is infinite im edance across the terminals of the secon ary S, permitting the transfer of energy'of desired frequencyfrom the antenna path into the'in ut circuit of the'tube V at substantially its ull or normal value through the coupling P, S. The oscillations of undesired frequency, transferred through the mag-,

netic couplling P, S, find a path of low'reactance t rough the switch a and L, G which is not opaque to them, and in conse quence the oscillations of undesired frequency effect only reduced electro-motiveforces as impressed upon the terminals of the condenser C Such electro-motive-iorce as is impressed by the undesired oscillations upon the terminals of the condenser O is neutralized by suitable adjustment of the capacitative-coupling condenser O. In

- consequence, with the switch 8 closed, the

undesired oscillations have no efiect upon the input circuit of the tube V, while the oscillations of desired frequency are impressed upon that input circuit substantially at their full magnitude through the magnetic couping.

When capacitative couplin s of thecharacter indicated in Figs. 7 an .8 areutilized, it is of some benefit to connect the secondary .circuits to earth or counter-capacity E, as

indicated. A

In Fig. 8 there is shown an arrangement in general similar to that of Fig. 8, except that the inductance L and C, in series with each other, and attuned to. the undesired frequenc or to the same natural period as thatoft e antenna path, forms, as regards the undesired oscillations, a short circuit of the secondary S. Here a ain the antenna is detuned as above descri and'the. secondary circuits, 0. is attuned to the deupon closure of the switch .9

p U sired frequen '[lpon closure of the switch a and i,

stantially only oscillations of desired frequency'transferred by thema etic couplingP, S are im ressed u on t e in ut cir cuit of the tube since w ile the pat L, 0 is of zero reactance for the undesired freuency, it is of high impedance or reactance or the desired frequency. With the switch s closed, such electro-motiye-forces as may be impressed upon the terminals of the con-- denser C through the ma the undesired frequency is or may he neutralized by adjustment of the capacitative coupling condenser, C". In this instance again, therefore, the undesired oscillations have little or no effect -upon the input circuit of the tube V, while oscillations of dezired frequency have substantially full ofect. Y

cuit of the tube V includes again the tuning condenser G and the inductance L, Energy of both desired and undesired frequencies is transferred from the circuit S, C to the input circuit of the tube V through the oppositely disposed capacitative cou ling condensers C and G", the halves of t e secondary S and the conductor 0. In the capacitative coupling branch including either of the condensers G or 0", but, as indicated, in the branch with G, is the parallel resonance path comprising the inductance L and condenser ,C to be attuned to the freuency of the desired oscillations. g With the switch 8 closed, rendermg L, C inefiective, and with the circuit 8, C detuned with res ectto the desired fre uency, and the ca'acitative cou lings C, 1 unbalanced, eibctrc-motiveorces cor 0nding with both the desired and undesirew frc- I the couplers C, C", a balance is efiected,

C" being attuned to the aforesaid natural period of the antenna, subgnetic coupling by InFig. 9 is shown an arrangement in 1 whereby no electro-moti ve force of either the desired or undesired frequency is impressed across the points 02 and 3 Upon opening the switch s',.thereis then broughtinto the capacitative couplingJ branch with the condenser C" a high or an stantlally in? finite im edance as regards oscillations'of .desired equency, with the r'esultthat the former balance of the capacitative couplings is upset, and oscillations of desiredfrequency are transferred through. the capacitative coupling including the condenser C to the input circuit of the tube V. Simultaneously, however, the branch G, L ofi'e'rs low im-. pedance to-the undesired oscillations,- which permits the condenser C to continue to effect with the condenser C a balance as regards the undesired oscillations, which'are accordingly withheld from the tubeV.

From the foregoing description 016 86- eral examples of embodiments of my invention, it is apparent that the circuit for translating the oscillations of desired frequency into signals or controls is in effect,

by suitably related couplings, out of ener absorbing relation with respect to t e antenna or other absorption path or conductor for all frequencies other than the desired frequency. The width of the-band or ran e of desired frequencies which will the translatin circuit becomes narrower or smaller as 51o capacity of the condenser C' is made great as compared with the inductance of L in the parallel resonance paths of the character utilized in Figs. 1, 1 2, 5, 6, 7, 8 and 9; and such band or range of desired frequencies reaching the translating circuit will become narrower orsmaller as the inductance L is great as compared with the condenser C in the series arrangements such as utilized in Fi 3 and 4. And in an arrangement of the c aracter indicated in Fig. 8. where L and C are in series with each other but tuned to the static frequenc it is preferable that the band or range 0 static frequencies withheld from the signal-translating circuit shall be relatively broad, ,and for this'nurpose the capacity of condenser C should be relatively greater and the inductance L relatively smaller than in the cases of Figs. 3 and 4.

It is further preferable that the circuit or path which is detuned with respect'to the esired frequency should have a natural period differing widely from the period of the desired oscillations and the couplings,

whether ma etic or capacitatii e, or both, are of such egrees of closeness or tightness that nevertheless a si al or response in the translating circuit 0 practically the usual or normal magnitude may be obtained.

In the case of absorption by the antenna or equivalent of energy of frequency hi her than the desired frequency, and especially when, as aforesaid, the condenser C has large capacity while the inductance L is small, in those arrangements in which they form a parallel resonance path, as in Figs. 1 etc., the parallel resonance path ofiers low impedance and the characteristic, balance described still obtains as to such higher frequencies. I i

For the sake of brevity in the appended claims, the term signal is'employed gener ically toinclude si nals of any character, includin telegraphlc and tele. honic signals, an any other analogous e ect, including controls; and the term static is gonerically employed to include static and other natural electrical effects and other effects having artificial origin and such as cause or are represented by waves or oscillations other than those representing the desired signal or control.

What I claim is: 1. In the reception of signals represented by high frequency energy, the method which comprises receiving the signal energ in a path having a natural frequency d1 fering from the frequency of the received signaloscillations, efi'ecting between a translating circuit and said path-opposing couplings preventing impression of signal oscillations and oscillations of different frequency upon said translating circuit, and changing one of said couplings as regards its balancing eifectfor signal oscillations to effect their impression upon said translating circuit to the substantial exclusion of the" oscillations of different frequency.

2.- The method of reducing the effect of static in the reception of signals, which comprises receiving the signal oscillations in a path detuned to the signal frequency and in which occur static oscillations of frequency different from the frequenoyof the signal oscillations, effecting between a signaltranslating circuit and said path opposing couplings preventing impression of signal and'static oscillations upon said translating circuit, and changing one of said couplings.

its balancing eflect for signal oscillations.

without affecting the natural period of said path to effect their impression upon said translatin circuit to the substantial exclusion of t e oscillations of difierent frequency.

, 4. The method ofreducin the effect of static in the reception of signa s, which comprises receiving the'signal oscillations in'a path detuned to the si al frequency and in which occur static oscillations of frequency different from the frequency of the signal "oscillations, effecting between a signal oscillations without aliecting the,natura1' translating circuit and said path posing couplings preventing impression 0 signal and static oscillations upon said translating circuit,'and changing one of said couplings as regards its balancing efl'ect for signal period of said path to effect their impression upon said translating circuit to. the substantial exclusion of static oscillations.

5. In the reception of signals represented by high frequency energy, the method which comprises receiving the signal energy in apath having a natural frequency differing from the frequency of the received oscillas tions, efi'ecting between a signal-translating circuit and said pat-l1 opposing couplings preventing impression of signal oscillations and oscillations of different frequency upon said translating circuit, and changing one of said couplings by a path comprising inductance and capacity tuned substantially to one of said frequencies to effect impressionof the signal oscillations upon said translating circuit substantially to'the exclusion of oscillations of different frequency.

6. In the reception of signals represented by high frequency energy, the method which comprises receiving the signal energy, in a path having a natural frequency dlffering from the frequency of the received oscillaticns, efl ecting between a signal-translating circuit and said path opposing couplings preventing impression of signal oscillations and oscillations of different frequency upon said translating circuit, and changing one of said couplings by a path com rlsin inductance and capacity tuned su stantially to the frequency of the signaloscillations to eflect impression of the signal oscillations upon said translating circuit substantially.

to the exclusion of oscillations of difi'erent hequency. I

7. In the reception of S1 als represented by high frequency energy, t e method which comprises receiving the signal energy in a pathhaving a natural frequency lower than cuit an alone of lower requenc the frequency of the received oscillations,-

efiectin between a signal-translating cirsaid path opposing couplings preventin impression of signa oscillations'and the oscillations of lower frequency upon said translating circuit, and changing one of said couplings by a path comprisin inductance and capacity tuned substantial y to one of said frequencies to effect impression of the signal oscillations upon said translating circuit substantially to the exclusion of oscilla- 8. In the reception o si als represented by high frequency energy, t e method which comprises receivmg the signal energy in a the frequency of the receivedbscillations,

' effecting between a. signal-translating cirdestroyin acting the oscillations of lower frequency upon said translatin circuit, and changing one of said couplings y a path comprising inductance and capacity tuned substantially to the frequency of the signal oscillations to effect impression of signal oscillations upon" said translating circuit substantially to the exclusion of oscillations of lower frequency.

9. The method of reducing the effect of static in the reception of signals, which comprises receiving the signal oscillations in a ath having a natural frequency dilfering rom the frequency of the received oscillations, efl'ecting between a signal-translating circuit and said path a balance preventing impression of signal oscillations and static oscillations upon said translating circuit, and destroying balance by a parallel resonance path comprising inductance and capac ity tuned substantially to one of the frequencies to eilcct impression of the signal oscillations upon said translating circuit substantially to the exclusi'onof static oscillations. 1 I,

10. The method of reducing the efi'ect of static in the reception of signals, which comventing impression of signa oscillations and.

prises receiving the signal oscillations in a/ path having a natural frequency lower than the frequency of the received oscillatlons, effectin between a si nal-translating 0'11- cuit an said path a ba anc'e preventing impression of signal'oscillations and static oscillations upon said t anslating circuit, and

the balance by a parallel resonance pat comprisin inductance and capacity tuned substantial y to the signal oscillations to efiect impression of the signal'oscilations upon said translating circuit substantially to the exclusion of static oscillations.

11. A receiving system comprising a path traversed by signal oscillations and detuned with respect thereto, a signal-translating ciredit, a system balanced as ,to signal and static oscillations to prevent their impression upon said translating circuit, and means for upsetting the balance of said system w th respect to signal oscillations to sheet their impression upon said translating circuit sub stantially to the exclusion of statlc osclllations.

12. A receiving system conipnsmg a path traversed by signal oscillations and detuned with respect thereto, a signal-translatmg c1 r cuit, a pluralityof couplin s between sa d translating circuit and said path and cosigna and static oscillations to prevent their impression upon said translating circuit, and meanlfor upsetti said balance to efi'ect. impression o si translatin circuit substantially to the exclusion o static'oscillations,

to efi'ect a balance with respect to a oscillations upon said 7 13. A receiving system comprising a path traversed by signal oscillations and detuned with respect thereto, a" signal-translating circuit, a plurality of couplings between said translating circuit and said path and co-acting to effect a balance with respect to signal and statig oscillationsto prevent their impression upon said translating circuit, and means comprising inductance. and capacity tuned substantially to one of said frequencies to upset said balance and effect impression of signal oscillations upon said translating circuit substantially to the exclusion of static oscillations.

14. A receiving system comprising a path traversed by signal oscillations and detuned with respect thereto, a signal-translatingcircuit, a plurality of couplings between said translating circuit and said path and co-acting to effect a balance with respect to signal and static oscillations to prevent their impression upon said translating circuit, and means comprising inductance and capacity tuned substantially to the frequency of the signal oscillations to upset said balance and effect impression of signal oscillations upon said translating circuit substantially to the exclusion of static oscillations.

15. A receiving. system comprising a path traversed by signal oscillations and detuned with respect thereto, a signal-translatingcircuit, a plurality of couplings between said translating circuit and said path and .co-acting to effect a balance with respect to signal and static oscillations to prevent their impression upon said translating circult, and means comprising a parallel res- "onance path attuned to the signal oscillations to upset said balance andeflect impression 'of signal oscillations upon said translating-circuit substantially to the exclusion of static oscillations. v

16. A receiving system comprising a path traversed by-signal oscillations and tuned to a frequency lower than the frequency of the signal oscillations, a signal-translating circuit, a plurality of couplings between said translatin circuit and said path and co-acting to e ect a balance with respect to said signal and static oscillations to prevent their impression upon said translating circuit, and means comprising inductance and capacity tuned substantially to the frequency ofthe signal oscillations to upset said balance and effect impression of signal oscillations upon said translating circuit substantially to the exclusion of static oscillations.

17. A receiving system comprising a path traversed by signal oscillations and tuned to a frequency lower than the frequency of the signal oscillations, a signal-translating.

circuit, a plurality of couplin s between said translating circuit and sai path and to said signal and static oscillations to prevent'their impression upon said translating circuit, and means comprisin resonance path tuned to the signal oscillations to upset said balance and effect impression of signal I oscillations upon said translating circuit substantially to the exclusion of static oscillations.

18. A receiving system comprisinga path traversed by signal oscillations and detuned with respect thereto, a signal translating circuit, a'magneticcoupling and another coupling between said translating circuit and said path and co-acting to effect a balance with respect to signal and static oscillations to prevent their impression upon said translating circuit, and means for upsetting said balance to effect impression of signal oscillations upon said translating circuit substantially to the exclusion of static oscillationsi 19. A receiving system comprising a path traversed by signal oscillations and detuned with respect thereto, a signal-translating circuit, a plurality of magnetic couplings between said translatin circuit and said a parallel path and co-acting to e ect a balance with c traversed by signal oscillations and detuned with respect thereto, a signal-translating circuit, a magnetic coupling and another coupling between said translating circuit ect impression of signal oscil and said path and co-acting to effect a bal- 1 ancewith respect to signal and static oscillations to prevent their impression upon said translating c rcuit, and means compris- .ing inductance and capacity tuned substantially to one of said frequencies to upset said balance and effect impression of'signal oscillations upon said translating 'circuit substantially to'the exclusion of static oscillations.

21. A receivingsystem comprising a path traversed by signal oscillations and detuned with respect thereto, a signal-translating circuit, a plurality ofmagnetic couplings between said translating circuit and said path and co-acting to eifect a balance with respect to signal and static oscillations to prevent their impression upon said translating circuit, and means comprising inductance and capacity tuned substantially to one of said frequencies to upset said balance and effect impression of signal oscillations upon said translatin circuit substantially to the exclusion 0 static oscillations.

j zoircuit a soup or n gwithvone c said O HP A receivin comprising a path traversed by sig al oscillations and detuned circuit, ar-plurality ct Amagnetic'hcou lin 1'" btW69l1 -S8,1d translatin circuit an said pathiand co-acting to: e ectza balancewith respect toisignaland-static oscillations. to- I j-prevent-theirimpression upon said translatmg circuit, and means comprisin a parallel Jrcsonance path attuned to the signal oscil- -.-l ations to upset theirbalance and effect im- -pnession of--.-signal oscillations uponssaid translating circuit substantially to the ex- ;clusion of. static oscillations. It ,123. Areceivings stemcomprisin aspath vtraversed by signs oscillations an tuned to a frequency lower than the frequency of lathe signal oscillations, a signal-translating circuit, a;= lurality otma netic cou tings. flfi hetween -sard translatin circuit. an said path-and co-acting to e ect' .a balance-with :a'espactrto said signaLand static oscillations ta vent-theirimpression uponsaid trans- :latmg-circxfit, and meanscomprisingra. ar-

2 allel .resonanoea path tuned'zto-the sign oslcillations to :upset ,said .balance and efiect al oscillations upon .--said --imp ression of -si =translatin circuitsubstantially to the extraversed by-signal oscillationsami detuned rwitln nespect qthereto, =a signal-translating --circu1 t, a. ?ste1n -.-comprising a plurality o oou hugs. alanced as tcwsignalqand static osc ation's to;- ,preveut;.efiect thereby. upon said x-translatin -.-circuit,.- and. means in ciricuit withone-o said couplingitunedn-tc one let the trequencies forzupsettmg the balance sand-tastiest impression on said translating 0 circuit ot-signal oscillations; substantially togtgmixclusioniotistatiecscillationa h a Wmgcsystemcompmsmga pat traversed Joy signal awcillationscandsdetuned Wlth respect} thereto, \acsignal-transhting ling-between-saidmranslating and sa,1d-.path,;an.-.epposing couplin ibetwwnnsaid translating-i circuit; and ssai signal and,-s.tatic oscillations .to-tprevent et- 5 fleet-thereby aspen said translatmgtcircuit,

ian'dzmeans ii-nrzcircuit -w1th one of; said,=cou- Ephngs; tuned to-one oigthe upsetting the .balance (and impressmn ns aadatranslctlng.circuit ct fgagnal oscillations substantially-to thecxclumw of static oscillations. v 26. A1 receiv ng: system icgrnpr sing a .path traversed by s1 al oscillations and detuned with respect t ereto, a signal-translatin .6 cirmt t, asgysteincomprising a plurality 0 con lings balanced as to signs and static osc1 nations to prevent efiect thereby upon said-translatin circuit, and means in citytuned to the frequency of the signal oscil ations for u couplings balanced as to'signa Sand attuned to one otthe ireguencies for .upsetting the balance and to e traversed by'si naloscillations and detuned with respect t rcto, a signal-translating .circuit, atsystem comprising ,zand -,at.tuned =to' the frequency of the. sign oscillations for upsetting efiect impression onsai I oisigmal escillationszsubstantially to. the

.circuit, asystem com rising a couplings balanced as to signa I I I I 0 O .saids translatmg circuit, .means 111 circuit witliatrespect t circuit, a. coupling between said translating setting awe-balance and to, efiect impression I on said translatin circuitof signal oscil- *Wlth respectthereto, ,a. signal-translating static oscillations. v I

27 A-receivingsystem comprising. alpath traversed by si al oscillations and detuned with respect t ereto, a signal-translatin circuit, a system comprising a 1pluralityo .and static oscillations-to prevent efie'ct thereby; upon zsaid. translating circuit, and inductance and 5 capacity in .parallelwith each other and in series 1n the circuit of one of said couplings ectimpression on said translating circuit of. s1gn al oscillations substantially to the GXOIIISIOII of static oscillations.

28. A receiving. system comprisingapath a. plurality of con lings-balanced as to-signa'l and static osci lations to prevent efiect nthereby. upon said translating circuit, andfinductancev and capacity in parallelwith each other and in series :in the circuit .ofone of said couplings al the balance an to translating circuit 5 exclusion of static oscillations.

29. A receiving system. comprising a path traversed by si a1. oscillations and detuned with respect. ereto, a. signal-translatm lurality o and static one to, prevent-efiect thereby upon withone .of saidcouplingsfor attuning to the signalloscillationaand means in circuit with another of said. couphngs tuned to one :01 the frequencies forupset'ti the balance iand to effect. impression onsai translating circuit of signal oscillationssubstantially to the exclusion of, static oscillations.

' 1 30. .A,.rece1vmg.system comprising apath itrasersed by si aLOSQIHILtlODSfiIId. .detuned ereto, a signal translatmg 11 ath, an opposing coucircuit a and said i translating. circuit and pling between .sai

-;said path for.,efiectingb alance withrespect to signalqand static oscillations to. prevent efiect thereby. upon-said translatinglcircuit,

means 'in-acircuit :with one of said couplings for tuning to, the -Slgl'l81l .OS0111atl01l S, rand means .izncircuit-avitnanother of, sa d cou- .pl ngs tnneditocm 102E. theatre uencies for ups tting the halance and to. e ectampres sion on said translating circuit of signal oscillations substantially to the exclusion of static oscillations,

. 81. .A receiving system comprising a path traversed by signal oscillations and detuned 13 cou lings balanced as to slgna osc' ations to prevent eflect thereby upon first respect thereto, a. signal-translatin circuit, a system comprising a 1plurality and static said translatin circuit, means in circuit with one of sai couplings for tuning to the signaloscillations and means in circuit with another of said couplings tuned tothe freof'the signa oscillations for upsett1n e balance and to effect impression on sai translating circuit of signal oscillations substantially to the exclusion of static oscilations.

a 32. A receiving system comprising a path traversed by signal oscillations and'detuned with respect thereto, a signal-translating circuit, a. system comprismg a upllings balanced as to sign and static 1 ations to prevent effect thereby upon said translating circuit, means incircuit with one of said couplin' for tuning to the signal oscillations, an inductance and capacity in parallel with each other and in series in the circuit of another of said couplings and attuned to one of the fre uencies for upsetting the balance and to e ect impresslon on said translating circuit of signal con lings balanced as to signa oscillations substantially static oscillations.

33; A receiving system comprising a'path to ;the exclusion of traversed by signal oscillations and tuned to:

a freguenc lower than the frequency of the signa osci ations, a signal-translatlng circuit, a system comprising a plurality of couplhngs balanced as to signal and static osci ations to prevent efiect thereby upon and translating the signal oscillations, and means in circuit with another of, said couplin tuned to the frequency of the signal oscil settmg the balance and to effect impres men on said translating circuit of signal oscillations substantially, to the exclusion of static oscillations.

34; A-receiving system comprising a path traversed by si%1al oscillations and detuned w1th respect t ereto, a signal-translating circult, a system comprising a plurality of and static osci lations to prevent efiect thereby upon and translating circuit, means in circuit with one of said couplings for attuning to the signal oscillations, means in circuit with another of said couplings tuned to one of the frequencies for upsetting'the balance and-to efiect impression on said translatin circuit of s1 al "oscillations substanti' y to the exclus on of static oscillations, and a reaetance in' circuit with jsaidoneof said plurality of a v I magnetica lg circuit, means in circuit with one of said couplings for attuning-to ations for 7 upwi said intervenin of signal oscillations substantially couplings for compensatingfor said means in said other of said circuits 35. A receiving system comprising a pathtraversed by siglnal oscillations and detuned with respect t eretoa signal-translating circuit, a plurality of circuits between said translating circuit and said path, means for coupling each of said intervening circuits to said path in senses to effect balance as to signal and static oscillations to prevent efiect, thereby upon said translating circuit, and

means in one of said intervening circuits tuned to one of the frequencies for upsettin the balance and to efiect impression on sai translating circuit of si al oscillations substantially to the exclusion of static oscillations.

36. A receiving system comprising a path traversed by si al oscillations and detuned with respect iiereto, a signal-translatin circuit, acircuit intervening between sai translatin circuit and said path, means cou ling said intervening circuit to sai pat means for tuning said intervening circuit to the frequency of the signal oscillations, a third circuit' coupled to said path and co-actin with said intervening circuit to effect ba ance as to si nalmagnetica y coupling said intervenin' cir'-' cuit to said ath, means for t said intervening clrcuit to the -frequericy 'of .thc

sigiial oscillations, a third circuit magnetica coupled to said path and co-acting circuit to efiect balance as to signal an static oscillations to prevent effect thereby upon said. translating circuit, and inductance and capacity in ari v allel'with each other in series in said t ird circuit tuned .to the frequency of the signal oscillations to upset said balance an to efiect impression on said translating circuit to the exclusionof static'oscillations.' 1

In imony whereof I have hereunto Davnic. Mm

my signature this 24th day of April, 

